This guide is specifically for cars with a manual transmission as the factory service procedures for an automatic cars require lowering the rear drivetrain.
Largely taken from Motorhead-47's post on the Corvette forums (some info directly copy pasted from their post.) I've added additional pictures / information taken from other source material listed at the bottom of this post.
SUGGESTED REPLACEMENT PARTS AS NEEDED
(Be sure to double check vehicle fitment, these were specific to my 2007 Base C6 Corvette)
- LEFT Sensor Kit (Replaces Part Number 19207710) - GM (19420829)
- RIGHT Sensor Kit (Replaces Part Number 19207711) - GM (19420830)
- Fuel Tank Sending Unit O-Ring - GM (21008100)
- Fuel Tank Sending Unit Lock Ring - GM (25691383)
- LEFT: Rear Auxiliary Fuel Feed and Return Pipe - GM (19431777)
- Fuel Tank Filler Vent Pipe Seal - GM (10376929)
- Crossover tube - 19431775 - GM (15223882)
- Vapor Canister Purge Tube - GM (12607115)
RECOMMENDED TOOLS:
- 7mm ratchet
- 13mm wrench
- 15mm wrench
- Screwdriver
- Zipties
- 5' of 3/8th inch rubber tubing
- Petroleum grease / White lithium grease
First a few fuel system basics; 
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When you fuel up, the driver's side tank fills first and when it is full the fuel spills over into the large crossover tube and then fills the passenger side tank
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The fuel in the passenger side tank is expended first by passing fuel over to the driver's side continuously via a pump driven purely off of fuel pressure from the electric fuel pump in the driver's side tank. It takes approximately 50psi or more for the fuel transfer function to work.
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When the passenger side tank is empty your gas gauge will read 1/2 full.
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There is a fuel level sending unit in each tank
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The last 1/2 of your fuel supply is in the driver's side tank.
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Your fuel pump uses the recirculating fuel to cool the pump. The lower you let your fuel level get the less cooling of the pump. Guys who continuously run down below a 1/4 or less can expect a shorter fuel pump life.
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The manual transmission has more room around the sides to work than the automatic.
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On automatic transmission cars the factory service procedures call for lowering the rear drivetrain.
#1. BEFORE YOU START - REMOVAL OF FUEL LINE
To get to the fuel pump the driver's side tank must be removed from the vehicle...there is absolutely no other way to get to it. It has to come out of the top of the tank and no, you can not cut a hole from above to access it.
You really want to start the job with as close to an empty fuel system as reasonably possible. Absolutely do not work with more than 1/2 a tank because I know of no way to easily get the fuel out of the passenger side tank.
You need about 24" of clearance under the car to get the tank out. A set of 6 ton or larger jack stands should get you there.
If you are pulling both tanks then you need to remove both rear wheels. You don't need to drop the passenger side tank to remove the pump in the driver's side though
Assuming you have less than 1/2 tank the technique I use to remove the rest of the fuel in the driver's tank is to let the fuel pump do the work for me. Of course this doesn't work if you have a dead pump. In that case you are stuck with the siphon it out as best you can method. Each gallon weighs about 7lbs and works against you later in the effort so best to get as much out now as you can.
If your current pump is still working what I do is disconnect the fuel line under the hood at the metal pipe at the firewall. I then slip a 5' piece of rubber 3/8" fuel line over that metal line and put the other end in a large gas can setting on the floor.
First remove the line clip located at the firewall connection.Place some old rags or paper towels under the line as gas will leak once you pop off the line.
When ready, use a fuel disconnect tool to pop off the line.
Connect your 3/8th tubing to the now disconnected line.
Have your tubing feeding into a gas tank placed on the ground.5' of hosing should be more than enough.
Using some wires and a 5amp fuse, combine to make this contraption. Although the fuse isn't 100% necessary, it's an added failsafe. You could technically jump directly with a wire.To get the fuel pump to run continuously without the car running you will have to jumper across two terminals of the fuel pump relay under the hood in the fuse box.
The pump relay is #55 in the fuse box.
NOTE: Pay attention to the orientation of the fuse before you pull it (TAKE A PICTURE)
Once you've done this you simply turn the ignition to the start position (don't crank the motor over) and let the fuel pump run the driver's side tank dry for you.When the tank is dry shut the car off and DISCONNECT THE BATTERY NEGATIVE TERMINAL!
Reconnect the fuel line to the fuel rail with the clip. Store the gas can in a safe place.
#2. LET'S PREP TO REMOVE THE FUEL TANK
Next remove the driver's side rear inner fender liner. (7mm ratchet tool) It's just a few fasteners that are pretty obvious.
Remove the inner wheel fender lining.
Additionally, to make this job easier, it's suggested to remove the H pipe. (15mm and 13mm wrench)
While you have the wheel well out, take a look at the fuel tank ground connection.Unbolt it - clean it up with some sandpaper for a better connection. After threading the bolt back in, spray with some black spray paint / anti-corrosion paint to prevent rust.
From below, the tank is held in position by the five 13mm bolts that hold the aluminum panel under the tank.
These five bolts are the only physical/mechanical connection that secure the tank to the car. Go ahead and remove those five bolts. Not to worry though because your empty tank won't move yet, It is held up by the crossover tube.
At this point you need to disconnect the fuel filler hose and the vent return hose at the fuel filler neck.The filler hose coupler is a simple hose clamp and the vent line has a quick disconnect fitting that works by pushing in with your fingers on the wide spot of the tan/white connector.
Sometimes it is easier to get those disconnected by first pressing the connector and then pushing in as if reconnecting the fitting and followed by pulling it apart. The in then out motion seems to release the tension on the connector
In the same general area as the fuel filler you will see a 4 pin connector with larger gauge wires on the outer pins and smaller gauge wires on the inner pins. The outer wires are the positive and ground wires for the electric fuel pump and the two inner wires are for the fuel sending unit FYI. This connector should be attached to the chassis with a barbed connector. Unplug that connector. It's not obvious to the eye but the portion of that connector that is/was attached to the car was the chassis side of the harness. The unsecured/loose end of the connector is the wiring harness to the fuel pump itself.
Be sure to also remove the EVAP line to the left by pressing the clip and pulling down as well as the electrical connector.
Next disconnect the fuel line that snakes it's way down the rear of the tank.This requires the same fuel line disconnect tool that you used under the hood to release the fuel line when you drained the tank.
When disconnecting the fuel line from the tank, it's a good idea to insert that 3/8th inch tubing to the now hanging line so gas isn't dripping anywhere.
#3 THIS IS WHERE IT GETS DIFFICULT.
You need to unlatch the crossover tube. To do this you will be working in the blind.
Study the following images to understand what the connector looks like and how it latches.
**I suggest using an Endoscope / Borescope during this process for a better look at how the clips attach / detach.
Should the crossover tube get damaged
Replacement part #
15223882 GM Genuine parts - Fuel tank crossover hose
Looking up from below this is what you will see.
This is the collar you will turn once you have unlatched the locking ring of the fastener. Before you disconnect these pieces, follow the dotted green line and using a marker MARK A LINE ACROSS with some type of sharpie to be re-aligned during re-installation.
Once you have the tab out of the way simply reach up and turn the couple counterclockwise to disconnect the fitting. You don't need to turn it very far...maybe 20 degrees or so. It does not unscrew. It is a short counterclockwise movement.
At this point the the crossover tube needs to be separated from the nylon fitting in the tank. This is done by pulling it directly out of the fitting. Not so easy though as it isn't possible to collapse the metal crossover tube. You need to do a few simple things that will give you the needed 3/4" or so of play.
What I do is go over to the passenger side tank and drop the 5 bolts holding the aluminum pan under the tank. This results in some tension on the crossover tube in the direction of the passenger side tank (A good thing)
Next reach up above the transmission and you will feel a spring loaded c-clamp type fitting that the crossover tube is snapped into. You can't see it but it is there. If you pull down on the crossover tube by hand the crossover tube should pop out of that spring loaded fitting.
Between this little bit of play gained in the crossover tube and the loose driver's side tank you should be able to pull the coupler out of the tank. It isn't easy and cuss words are the norm. Be careful that you pull directly back on the coupler to separate it because there are several fragile fuel lines on the inside of that coupler.
You still have one more line to disconnect before lowering that tank! There is a vent line above the tank that used the same type coupler as the vent you removed from the filler neck. Reach up above the tank and find that coupler and disconnect it.
You can now safely lower the tank out of the car!
#4 FINALLY THE TANK IS OUT!
With the tank removed, be sure to tape off any components that you don't want to get wet.With a wet towel and some compressed air, clean the tank the best you can to prevent debris from falling into the tank once you open it up.
There is a large metal locking ring that secures the fuel pump to the tank. You need to rotate it counterclockwise to unlock that ring. Ideally use a plastic mallet and a dowel to rotate the collar lose.Replacement part #s:
Fuel Tank Sending Unit Lock Ring - GM (25691383)
With the collar released you can then pull the pump HALFWAY out of the tank. To get the pump completely out you need to disconnect the line that goes forward to the passenger side tank and the second line that serves as the return line from the passenger side tank. The return line dumps into the white fuel pump bucket.
VIDEO HELP: Removing / dissemble of the tank: 14:50
https://youtu.be/XN3aXuK_VDU?si=-YUQfyzZYoIuuS18&t=896
VIDEO HELP #2: Pump removal video: 32:00
https://youtu.be/84s-Q4xBiy4?si=t3mJEKTppeP_Qj_N&t=1929
This is the line set that is in the tank. One end has the connector that you can release with your fingers and the other end is secured with a plastic hose clamp with it's end resting in the pump's sump.
If you look at the above photo closely you'll recognize that the other end of those two lines is what plugs into the nylon fitting at the top of the tank where the crossover tube mates up.
Double check that all of the O-rings are still there.
Once you have the two fuel lines disconnected you can then begin to fish the pump out of the tank. Be careful because you have a long fuel level float wire and float still attached to the pump.
I have found that the bottom half of the fuel pump seems to expand after it is installed. It can be a challenge to get the bottom half of the pump through the tank's opening. Sometimes it takes a bit of persuasion with a small screwdriver.
#5 FLOATER REPAIR
Most new fuel pumps do not come with the fuel level sending unit. This means you'll need to transfer over the old one.
Sensor Kit (Replaces Part Number 19207711) - GM (19420830)
Fuel level sending unit attached to pump. It just clips on and doesn't need any comment as to how to R&R it.
You'll need to remove the fuel sending unit wire leads from the old connector and plug them into your new fuel pump's connector.
The two smaller gauge wires on the left are the ones that have to come out. In the center of the back of that connector is a hole. Inserting a small jeweler's screwdriver allows you to release a lock which then allows the front of that wire connector shell to come off. From the front you insert that jeweler's screwdriver into the shell and release the tang holding those two wires in. The fuel sending unit wires then simply plug into the bottom of the new fuel pump connector. Double check to make sure they are secure. If not, you'll be doing this all over again for a "no gas gauge" problem.
VIDEO HELP of the floater replacement: 34:40
https://youtu.be/84s-Q4xBiy4?si=mPo6lPCWff0_VBkM&t=2087
#6 RE-INSTALL THE REPAIRED FUEL PUMP!
You are now ready to install the pump back in the tank.
Don't forget to attach the fuel level float to the sending unit.
Getting the pump back in and the in-tank fuel lines connected is a bit of a Chinese puzzle.
Before placing the pump back in, double check that the rubber grommet at the bottom of the fuel pump is still attached.
Now would be a good time to replace that green o-ring
Fuel Tank Sending Unit O-Ring - GM (21008100)
Re-installing the pump assembly: 18:50
https://youtu.be/XN3aXuK_VDU?si=PO79Zw1-RV2piSok&t=1133
Attach a piece of safety wire to the loop of one of the inside lines and the other end of that wire to the connector on the other fuel line. Let the wire hang outside of the fuel tank opening. Now insert the pump halfway into the opening being sure not to get the fuel level float bound up on the lines in the tank.
Using the safety wire, pull the two lines in the tank to where you can reach them with your fingers and attach the clip on the one fuel line to it's fitting and then insert the return line into the fuel pump bucket and secure it with the nylon fastener you removed earlier.
When feeding this back into the pump, make sure it's re-attached to the bracket inside the tank.
Feed the line through the bracket inside the fuel tank line so.
If you notice a gas smell in your car, these o-rings are probably leaking.
Replacement part #:
GM 10376929 Seal, Fuel Tank Filler Vent Pipe
If the clips snap, you can use zip-ties to hold the fuel lines in place.
Make sure the floater is not caught up, distorted, or bent during re-installation.
Using a flashlight, look inside the tank and make sure the bobber is able to move freely.
Once set in place, wipe down for a last time and put a light layer of petroleum grease. This will help everything fall into place when you get ready to attach the crossover tube.
VIDEO HELP:
https://youtu.be/XN3aXuK_VDU?si=sVLmmCu5a1JcAGAg&t=1292
Before you go any further, check your work and take a close look at the stack of spacers, o-rings, etc. in the above photos.
Be sure this is 100% correct as these connections are critical!
Make sure you have not lost any of the 3 pieces that seal the
crossover tube to the tank.
CHECKLIST
At the rear is a black o-ring followed by a green o-ring followed by a tapered ferrell.
Also, look closely at the two fittings that carry fuel to the passenger side tank. There should be a plastic ferrel with an o-ring behind each.
Also make note of the T-shaped hole between the forward and return lines.
The crossover tube has the male counterpart to that T to align things properly.
With that all done you can remove the safety wire, drop the pump in the rest of the way, and then secure it all up with the large metal lock ring you took off earlier.
You are now ready to put the tank back in the car!
#7 YOU ARE NOW READY TO PUT THE TANK BACK INTO THE CAR!
Using a light amount of petroleum grease for the outer hose nozzle and the smaller inner hoses so they slide in easier and fill any imperfections on the o-rings.
Using your previous markings, or make some new ones, be sure to mark a line across the top crossover tube hose that aligns with the placement these hoses inside the tank.
Before re-installing the tank(s) into the car be sure to make sure everything is correctly plugged back in.
Like the breather hose at the top of the tank.
Slip the tank under the car, raise it up by hand, feed the wiring harness over to the filler neck area, get the filler neck in position and loosely support the tank with something.
Reach above the tank and reconnect that vent line that you can't see
Raise the tank up and with one hand moving the tank and the other hand on the crossover tube coupler you should be able to plug the crossover tube coupler into the tank. If things are aligned properly it should drop right in. You'll know if it is right because you'll be able to easily lock the coupler with a short clockwise turn.
Attach the fuel line from the tank to the hard line that leads to the engine compartment
Attach the fuel filler neck and vent tube
Connect the fuel pump harness to the chassis connector
Put the 5 bolts back in each (driver and passenger side) of the aluminum pans that support the fuel tanks
Put fuel back in the tank
Before buttoning it all back up and taking it off the jack stand I'd go ahead and reconnect the battery. Don't forget to reinstall the fuel pump relay. When you first turn the key on the fuel pump will only run for a few seconds to prime the line. This is normal. The pump will not run full time until the car starts.
Fire it up!
If you did it all correctly then this is what you should see at the fuel rail connector
SOURCES:
MOTORHEAD-47's POST:
VIDEO 1 By Z06 Baron:
VIDEO 2 By Z06 Baron:
VIDEO 3 By Drew Mann:
VIDEO 4 By Last Corvette: